This invention relates to navigation systems for mobile robots or autonomous vehicles, and more particularly to a navigational apparatus and method for guiding an autonomous vehicle throughout a work area.
Robotic devices are commonly used to perform repetitive, difficult, or dangerous tasks that must otherwise be performed manually. One desirable application of robotics involves operating a vehicle within a work area to perform some task on the work area surface. Examples of these tasks are mowing lawns, or waxing or vacuuming floors. The robotic device in these operations must be navigated to efficiently cover the entire desired work area so as to perform the desired task while avoiding obstacles within the area.
A number of prior devices are adapted to cover a work area to perform some task on the surface of the work area. These devices include a mobile robot or autonomous vehicle carrying equipment such as a vacuum, for example, for performing the desired task. The vehicle or robot is navigated by a guidance system to cover the work area. There were numerous drawbacks, however, with the prior mobile robot or autonomous vehicle navigational systems. In some cases the mobile robots had navigational systems that caused the robot to follow a fixed guide positioned in the floor of the work area. However, these fixed guides were impractical in many situations. Other mobile robot devices required a built-in map of the work area indicating its various boundaries and obstacles. This built-in map was expensive in terms of time and inconvenience and limited the use of the device to work areas for which maps had been created. Still other devices had to be manually guided around the boundaries of the work area in a learn mode to teach the guidance system the boundaries of the work area. This required manual supervision that the device was intended to eliminate. Also, robots which operate from a preprogrammed map are incapable of coping with obstacles that are in conflict with the programmed work area. Other mobile robot or autonomous vehicle navigating devices did not require a fixed guide in the work area, built-in maps, or manually performed learn modes, but did require elaborate sensors and range finding devices to sense work area boundaries and obstacles and also required elaborate computer hardware. This elaborate computer hardware and sensor arrangement made these prior mobile robot navigational devices prohibitively expensive for many applications.